The present invention relates to semiconductor testing and testing devices. In particular, the present invention relates to a system for establishing contact between a device under test and a test socket.
During and after manufacture, integrated circuit devices are subject to exhaustive testing. After an integrated circuit device has been packaged, its contacts are coupled to the channels of an integrated circuit device tester. The tester applies a series of excitations to the device and analyzes the device""s responses. On the basis of the test results, the device can be graded and sorted.
Testing is desirably carried out rapidly, accurately, and in high volume. For these purposes, automated testing equipment has been developed. A typical testing system includes a device tester and a device handler. The device handler has a test contact system that picks up a device under test, using suction applied through a silicone vacuum seal, and places the device under test into a socket of the device tester. The test contact system applies a force against the device under test to establish and maintain electrical contact between the device under test and the test socket.
Where the device under test includes a die mounted on a substrate, the test contact system typically applies the contacting force against the die, which is at the center of the substrate. Particularly where the die is un-encased, as is often the case when the device under test is of the flip chip type, the die or the substrate sometimes cracks, resulting in a loss of the device under test. Devices under test can also be lost when a device under test sticks to the vacuum seal resulting in a handler jam.
There is an unsatisfied need for a device testing system that reduces the number of devices lost through handler mishaps.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention provides test contact systems and associated integrated circuit device testing systems, and integrated circuit device testing methods that reduce the number of integrated circuit devices that are lost through handler mishap. The invention provides a test contact system in which a contacting force, or a substantial portion thereof, is exert against the substrate of a device under test, rather than exerting the entire force against the die. The invention also provides a system for adjusting the distribution of the contacting force between the substrate and the die. This mechanism allow the force against the die to be kept within a range that provides good thermal contact between the die and the test contact mechanism without damaging the die. The balance of the contacting force can be transmitted to the substrate of the device under test through a resilient member, thereby further reducing the risk of damage to the device under test. The invention further provides a vacuum seal comprising a foam type material to which devices under test do not stick, which substantially eliminates handler jambs resulting from devices under test sticking to the vacuum seal. The test contact systems of the invention, and associated testing systems and methods, significantly reduce the number of integrated circuit devices damaged during testing.
One aspect of the invention provides a test contact system for exerting a contacting force against an integrated circuit device that comprises an un-encased die attached to a substrate, comprising a body and a contact plate supported by the body, wherein the contact plate exerts at least a substantial portion of the contacting force against the substrate of the integrated circuit device.
Another aspect of the invention provides a test contact system comprising a body, a resilient member, and a contact plate, wherein the body exerts a repelling force against the contact plate through the resilient member.
A further aspect of the invention provides a test contact system comprising a body and a vacuum seal attached to the body for holding a device under test to the body, wherein the vacuum seal comprises a foam type material.
A further aspect of the invention provides a test contact system comprising means for exerting a contacting force against an integrated circuit device, wherein the integrated circuit device comprises an un-encased die attached to a substrate and at least a substantial portion of the contacting force is exerted against the substrate of the integrated circuit device.
A further aspect of the invention provides a method of testing an integrated circuit device comprising , while testing the integrated circuit device, exerting a contacting force to hold the device under test in contact with a socket of a device tester, wherein at least a substantial portion of the contacting force is exerted against a substrate of the device under test.